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DX 80 and DX 70 RF Signal Containing Audio


In certain scenarios the Cisco DX80 and DX 70 platforms may emit an RF signal through its microphone or speaker that could carry audio from an active call. A user with the known frequency could configured a specialized RF analyzer and antenna to capture this signal. Cisco has only observed that this signal can be captured from 10-12ft from the device.

An RF signal can also be observed via the speaker of the device.  When playing at 70% of max volume (which would be higher than normal for an individual office using the speaker), RF emissions have been received and demodulated at around 6-10 ft distance of the DX80. Only the DX 80 is affected by the microphone RF signal radiation and not the DX70.

Note: The Cisco Webex Desk Pro or any other Cisco collaboration endpoints are not affected by this issue.

Using a USB Headset

Using a headset via USB to either of the products eliminates the speaker-modulated RF emissions, since the Cisco DX70/80 software stops sending audio output to the speaker in this mode. For DX70 this would be a sufficient workaround for a customer concerned about these RF emissions.  When attaching a USB headset, the microphone on the DX80 remains active and the microphone-modulated RF emissions remain unchanged. The software fix introduced in Cisco bug ID CSCvw28048 allows an administrator to turn off the power to the microphone on DX80s to avoid this unwanted signal to be emitted from the device.

Disabling the Microphone on the Cisco DX 80

Complete the following steps to upgrade the DX 80 and disable the DX 80 microphone.

Step 1: The upgrade is simply done from the web interface under the Maintenance tab.

Screen Shot 2020-11-04 at 11.57.21 AM.png



Step 2Once installed, you can connect via the web interface or via SSH. From the web interface, navigate to Setup > Audio.

Screen Shot 2020-11-04 at 11.57.34 AM.png


 Step 3: Scroll down to Input > Microphone and disable the microphone and turn off PhantomPower, as demonstrated below. 

Screen Shot 2020-11-04 at 11.57.42 AM.png


Alternatively, you can login via SSH as admin and execute the following commands:

xConfiguration Audio Input Microphone 1 PhantomPower: On
xConfiguration Audio Input Microphone 1 PhantomPower: Off

Note: The settings is still stored in EEPROM, so it will be remembered through a software upgrade. It is very important that you turn the mic back on (xConfiguration Audio Input Microphone 1 PhantomPower: On), before upgrading back to released code (if the microphone needs to be used in the future).





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